President Mugabe is fast losing his grip on the country and pressure is building on him to quit.

President Robert Mugabe is fast losing his grip on the country and pressure is building on him to quit. Here's what you need to know:

What is happening?

Mugabe, 93, has ruled Zimbabwe for 37 years and many claim his leadership has been repressive. He heads the ZANU-PF party and is the world's oldest head of state.

In a dramatic turn, the army placed Mugabe under house arrest on November 15 and there are now increasing calls for him to quit.

On Saturday, thousands are gathering in the capital Harare and the second city of Bulawayo to demand Mugabe's resignation in scenes that would have been unthinkable one week ago.

Why did the army target Mugabe?

The army insists it is not launching a coup, but on November 15, as well as placing Mugabe under house arrest, the military seized the state broadcaster and blocked access to government sites.

The takeover unfolded after Mugabe sacked Vice President Emmerson Mnangagwa on November 6 for showing "traits of disloyalty".

The ex-vice president is an ally of army Chief General Constantino Chiwenga and a veteran of the country's struggle for independence.

Many believe Mugabe sacked Mnangagwa to make way for his wife Grace to become vice president and eventually rule the country.

Army commander Chiwenga had warned that the military would act if purges against former war liberation fighters did not cease.

Who are the war veterans?

War veterans, who fought alongside Mugabe during the 1970s struggle for liberation from Britain and spearheaded the repossession of white-owned commercial farms in the 2000s, claim their president has betrayed the revolution.

The ongoing purges of scores of Mnangagwa allies have widened the rift between the Mugabes and various groups of war veteran leaders.

Victor Matemadanda, secretary-general of the Zimbabwe National War Veterans Association, recently said the ongoing expulsions were a strong indication that Mugabe was acting in his own interests and those of his wife.

Who's with and who is against Mugabe now?

As well as the army, opposition and war veterans, some members of Mugabe's own party have turned against him. All 10 of ZANU-PF's provincial structures have passed a motion of no-confidence against Mugabe and called on him to step down as the ruling party's first secretary.

If Mugabe fails to resign on Saturday, the party says it will convene a special committee meeting on Sunday in which the ZANU-PF Central Committee will consider the provincial resolutions to recall Mugabe.

Also on Sunday, regional dignitaries from the Southern African Development Community (SADC) are expected to meet in an extraordinary session to discuss the Zimbabwe situation in neighbouring Botswana, where the SADC headquarters is located.

SADC chair, South African President Jacob Zuma, is a close ally of Mugabe and was the first to talk to the leader after the military takeover.

While the region's leaders have been silent on Mugabe's fate, Botswana's President Ian Khama has openly called for the elderly president to step down.

Will Mugabe quit?

He has certainly lost his grip on power, but whether he will resign remains to be seen.

Mugabe made his first public appearance on Friday, two days after being placed under house arrest, as he attended a graduation ceremony. He is yet to make an official statement.

Reports on Friday citing unnamed sources close to mediation efforts said that Mugabe could be impeached if he fails to quit.

South African media has reported that a transitional government including the opposition could emerge, with sacked Vice President Mnangagwa at the helm. MWC News was unable to verify these reports.